Should I freeze my baby's stem cells?

It can't hurt - just don't expect any guarantees that they'll end up being useful.

Yesterday, Shamshad Ahmed, managing director of Smart Cells International, announced that his company could, for a princely £1,250, harvest the stem cells from the umbilical cord of your newborn baby and store them, frozen, for 25 years.

The company says that the cells would be useful in rebuilding organs, muscles and other damaged tissue if the child - or even a sibling - needs treatment for life-threatening illnesses.

None of this is theoretically wrong. Stem cells are the master cells of the body, with the ability to transform themselves into cell types of all kinds. All humans possess them - the umbilical cord is a plentiful resource - and stem-cell research raises the possibility that doctors will be able to grow tissue that exactly matches a person's own, thereby offering opportunities to replace bad cells and reduce the risk of rejection in the event of a transplant.

But while stem cells offer scientists an unparalleled research tool, there are some concerns that the potential for treatments has been oversold.

Fertility scientist Robert Winston waded into the debate earlier this year when he admonished researchers for making over-the-top claims.

Singling out predictions around embryonic stem cells in particular, he said that the hype would lead to unrealistically high expectations and an inevitably painful fall when scientists fail to come up with the breakthroughs.

Professor Dame Julia Polak, director of the tissue engineering and regenerative medicine centre at Imperial College London, believes that if parents have the money and they want to do it, there's no harm. But she warns: "There are no guarantees - there's a lot to be learned first. The studies have shown that cord blood stem cells have been used to treat leukaemia. So if a child is going to develop leukaemia, it's a good idea."

Scientists have also found that umbilical cord stem cells can become nerve or muscle cells but, so far, this change has only been achieved in petri dishes: there have been no animal trials yet and treatments for humans are still a distant dream.